The research proposed in this application is to ascertain the amino acid sequence of the H-2Kk histocompatability alloantigen expressed on the surface of ASL1-W murine leukemic cells. The first 30 N-terminal amino acid residues of H-2Dd will also be defined in order that comparisons of the H-2Kk and H-2Dd gene products to each other and to other membrane-associated components vital for cellular interactions between host-derived and malignant or transformed cell may be assessed. 10 to the 12th power cells per week will be produced utilizing large-scale mammalian cell culture to provide sufficient H-2Kk alloantigen for study. Isolation and structural characterization of the H-2 alloantigens will embody features of high pressure liquid chromatography and semi-micro solid-phase technology to permit rapid delineation of their amino acid sequence. These investigations will undoubtedly lead to a better understanding of the structural basis for receptor-recognition phenomenon involved in tissue compatability, differentiation, organogenesis, malignant cell transformation, virus susceptibility, and induction of the immune response to antigens. The majority of the methods and techniques developed in this project will be directly applicable to primary structure determination of other membrane proteins known to be important in both cellular and humoral immune responses.